Source Recombinant Human CD21 Protein is expressed from HEK293 with His tag at the C-terminal. It contains Ile21-Arg971.[Accession | P20023-1] Molecular Weight The protein has a predicted MW of 105.3 kDa. Due to glycosylation, the protein migrates to 110-130 kDa based on Bis-Tris PAGE result. Endotoxin Less than 1EU per μg by the LAL method. Purity > 95% as determined by Tris-Bis PAGE> 95% as determined by HPLC Activity ELISA Data: Immobilized Human CD21, His Tag at 0.5μg/ml (100μl/Well) on the plate. Dose response curve for Anti-CD21 Antibody, hFc Tag with the EC50 of 7.9ng/ml determined by ELISA. Formulation Lyophilized from 0.22μm filtered solution in PBS (pH 7.4). Normally 8% trehalose is added as protectant before lyophilization. Reconstitution Centrifuge tubes before opening. Reconstituting to a concentration more than 100 μg/ml is recommended. Dissolve the lyophilized protein in distilled water. Storage The product should be stored at -25~-15℃ for 1 year from date of receipt. 2-7 days, 2 ~8 °C under sterile conditions after reconstitution. 3 months, -25~-15℃ under sterile conditions after reconstitution. Recommend to aliquot the protein into smaller quantities when first used and avoid repeated freeze-thaw cycles. Note 1.Please operate with lab coats and disposable gloves for your safety. 2.This product is for research use only.